Less Brain Connectivity and Pain Inhibition in Fibromyalgia

A new study published in the 26 April 2012 issue of the Molecular Pain journal found that fibromyalgia patients had significantly less connectivity in the areas of the brain that are involved in modulating and inhibiting pain when compared with healthy controls.

The Route Pain Takes

Our bodies have both ascending and descending pain pathways. When a healthy individual receives an injury, the body sends a signal from the site of the injury, through the central nervous system, to the brain. This is the ascending pathway. Within the brain, the signal makes various connections, interpreting the nature of the injury. Once the signal reaches the higher centers of the brain, the descending control mechanisms are activated. At this point, the pain signal can be modulated or inhibited at various levels. The body releases chemical substances such as endogenous (internal) opiates and begins working to progressively reduce (inhibit) the pain.

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For individuals with fibromyalgia, however, there appears to be some disconnects in the brain, preventing the control mechanisms from being activated. Instead of modulating and inhibiting the pain signal, the body seems to magnify it. This study attempted to locate areas of the brain in which these disconnects are occurring.

Study Design and Results

In this study, researchers compared the functional connectivity of the descending pain inhibitory network in 42 subjects: 28 FM patients and 14 healthy controls. They performed functional magnetic resonance imaging (fMRI) while applying calibrated pressure pain to the right thumbnail of participants.

They found that the healthy controls had significantly higher connectivity to the amygdala, hippocampus and brainstem compared to the FM patients. The thalamus also showed significantly higher connectivity to the orbitofrontal cortex in the healthy controls. There were no regions of the brain in which FM patients had higher connectivity.

The researchers concluded, “The present study provides brain-imaging evidence on how brain regions involved in homeostatic control of pain are less connected in FM patients. It is possible that the dysfunction of the descending pain modulatory network plays an important role in maintenance of FM pain and our results may translate into clinical implications by using the functional connectivity of the pain modulatory network as an objective measure of pain dysregulation.”

My Thoughts...

It has long been apparent that fibromyalgia patients do not process pain normally. Instead of our bodies working to gradually reduce pain, they actually seem to magnify and spread the pain. I am encouraged by the fact that this study was able to identify the areas in our brains that are not processing pain correctly. Hopefully this may one day be used as a tool for diagnosing fibromyalgia and may help pinpoint targets for the development of effective treatments.